1. Technical Field
The present invention relates to backpressure control units for supplying a liquid to a main head unit of a liquid ejecting head that ejects the liquid from nozzle openings, and furthermore relates to liquid ejecting heads and liquid ejecting apparatuses that include such backpressure control units; the invention is particularly useful when applied in a backpressure control unit having a flow channel member.
2. Related Art
An ink jet recording head, which is an example of a liquid ejecting head, prints onto a medium such as paper by instigating pressure changes in pressure generation chambers that communicate with nozzle openings and ejecting ink droplets from the nozzle openings onto the medium. Providing a flow channel member, for supplying ink to a main head unit having the nozzle openings, in a valve unit (a backpressure control unit) has been proposed as an example of this type of ink jet recording head (see JP-A-2005-186344, for example).
In the flow channel member of the backpressure control unit according to JP-A-2005-186344, a plurality of backpressure control valves (for example, seven) having springs that adjust the pressure in individual flow channels are provided, and the entire unit is integrated as a single entity by being covered by a cover, formed of a resin, having positive water vapor barrier properties.
As described above, with the flow channel member according to JP-A-2005-186344, a plurality of rows are integrated and housed within the cover, and thus there is a problem, particularly when multiple colors of ink are used, where there are discrepancies among the properties of the backpressure control valves in each valve unit caused by warping and the like in the overall apparatus, including the cover. Furthermore, in the case where the number of rows is to be changed in order to increase the number of colors or the like, it is necessary to redo the overall design and change the process for manufacturing the unit as well. In other words, the flow channel member lacks generic applicability.
It should be noted that these problems are not limited to ink jet recording heads, and are also present in other liquid ejecting heads that eject liquids aside from ink.